He is far from masterful when paying in Midfield nor can he do it easily, he as more or less been an attacking is entire professional career he won't be able to just flip a switch and play Midfield, when he played midfield for liverpool they were even more explosive in attack but even more open in defense and for liverpool that is saying a lot
He will eventually learn to play in Midfield, and will be a great success for us,but it will take time to learn how to cover space better, how to rotate the ball better.
These aren't things he instinctively does, as he is way way more of an attacking midfielder let's say kaka type to make the example simplier, than he is a decision type, I'm trying to leave iniesta out of it.
1 bonus of signing him in January is that we have a house bunch of time to have him develop new habits and by next season he should have it.